http://www.backwoodshome.com/articles/silveira49.html

But what I want to know is...what really happened to the Australian president who disappeared at the beach?

Prime Minister Harold Holt, an avid skin diver was doing a weekend dive with friends at Cheviot Beach in the state of Victoria in December 1967. It is presumed the rough seas forced him into rocks in the area and he was knocked unconscious and drowned. His body was never found and was presumed swept out to sea making him the 3rd PM to die whilst in office. Now here's a country that knows how to treat its politicians.

However, conspiracy theorists inhabit Australia in abundance and there are plenty who firmly believe all sorts of conjecture from staging his own disappearance because of the stresses of the office to being picked up by a Chinese submarine (the Chinese have denied it). It gave birth to the Aussie phrase "Doing a Holt", meaning to disappear with no explanation (usually occurs when there is an unpleasant job to be done).

Interestingly enough an enquiry into Mr Holt's death was finally announced late last year. What it matters now is beyond me. (Story is here)

I remember hearing that a great white shark got him as he was wading on the beach.

No, that was former Prime Minister Gough Whitlam who was taken by a shark called John Kerr.